Biofeedback-assisted exercise in the rehabilitation of patients after total hip arthroplasty – effects on functional outcomes and quality of life

Intervention includes 21 day of inpatient postoperative rehabilitation after total hip arthroplasty (THA) according to standard protocol which consists of daily sessions of land-based exercise therapy, application of physical agents (interferential current therapy and electrostimulation), group aquatic exercise and individual education. Each of 21 days of rehabilitation follows the same protocol, except Sundays when patients do not receive physiotherapy (there are three Sundays during the patients' stay at the hospital). There are 18 days of rehabilitation consisting of: 50 minutes of land-based exercise, 30 minutes of aquatic exercise, 10 minutes of interferential current therapy, and 10 minutes of electrostimulation. All interventions are performed on a daily basis, except individual education. Programme of land-based exercise consists of 20 exercises. Patients perform 7 variations of isometric exercises for thigh muscles and 13 dynamic exercises for lower limb which include pelvic lift exercise from lying supine position (exercise 1), active straight leg raise from lying supine position with and without elastic band around ankles for the resistance (exercises 2 & 3), hip abduction with the knee in extension from lying supine position with and without elastic band around ankles for the resistance (exercises 4 & 5), hip and knee flexion from lying supine position with and without elastic band around feet for the resistance (exercises 6 & 7), hip and knee flexion toward the patient’s chin in lying supine position with patient’s legs on Swiss ball (exercise 8), shifting extended leg from Swiss ball on the therapy bed and vice versa in lying supine position (exercise 9), hip abduction with extended knee from side lying position (exercise 10), hip flexion and extension with knee extension from side lying position (exercise 11), knee flexion and extension from side lying position (exercise 12), knee extension from sitting position (exercise 13). Isometric exercise is performed in sets of 1, 5 repetitions with maximal effort lasting 5 seconds. Dynamic exercise is performed in 1-2 sets, 10 repetitions. Progression of dynamic exercise is achieved with elastic band and during the last 6 days of rehabilitation ankle weights (1kg) are included. Interferential current therapy is provided using Myomed 632 device (Enraf-Nonius B. V., Rotterdam, The Netherlands) in duration of 10 minutes using symmetrical waves, phase duration of 100 µs, phase interval 0 µs, impulse frequency 80 Hz, modulation frequency 0 Hz, modulation programme 1/1 sec, with intensity in mA according to patient's tolerance. Electrostimulation is provided using Myomed 632 device (Enraf-Nonius B. V., Rotterdam, The Netherlands) in duration of 10 minutes using symmetrical waves, phase duration of 500 µs, phase interval 0 µs, impulse frequency 1Hz, modulation frequency 0 Hz, modulation programme 1/1 sec, with intensity in mA according to patient's tolerance. Group aquatic exercise include 11 exercises for the range of motion and strength of the lower extremity muscles and include: standing heel raise (exercise 1), hip extension from standing position (exercise 2), semi-squats (exercise 3), hip flexion from standing position with the extended knee (exercise 4), hip and knee flexion from standing position (exercise 5), hip abduction from standing position (exercise 6), hip extension from standing position while holding the edge of the pool with hand (exercise 7), touching ipsilateral leg with the hand while the trunk is slightly bended forward (exercise 8), hip and knee flexion while floating on the water in supine position (exercise 9), hip abduction and adduction while floating on the water in supine position (exercise 10), and hip flexion with extended knee while simultaneously extending contralateral hip towards the bottom of the pool while floating in the water (exercise 11). Exercises are performed bilaterally. Individual education is mainly targeted to long-term care of the prosthesis regarding how to return to activities of daily life, recommended and non-recommended activities, coping with postoperative pain and prevention of blood clots by regular physical activity. It is provided by physiotherapists before and after exercise session, orally. Education is provided once, at the start of the rehabilitation, with additional explaining as necessary (if patients has questions). A portion of land-based exercise therapy will be biofeedback-asissted (Myomed 632, Enraf-Nonius B. V., Rotterdam, The Netherlands), with individually adjusted targets for muscular isometric contraction, according to manufacturer's instruction. Biofeedack is provided by superficial electromyography (EMG) unit, e. g. electrical activity of a muscle is registered and passed on as quantitative information (feedback) to the patient and the physiotherapist in real time, during exercise. That way, the patient is able to monitor the strength of the contraction on screen and try to achieve adequate intensity of the muscular isometric contraction. The device is attached to the patient via three electrodes, two EMG electrodes, and one reference electrode. The EMG electrodes are placed at ¼ th of the muscle belly of the anterior portion of the m. quadriceps femoris. The reference electrode is placed on the anterior portion of the tibia of the opposite leg. At the beginning of the biofeedback-assisted exercise the patient will perform maximal isometric contraction of the m. quadriceps femoris to establish the threshold, e.g. the target intensity of the muscular contraction. Sensitivity of the EMG signal is set to 200 µV to achieve good visibility to a patient, e.g. to achieve good graphical representation of the muscle's electrical activity on the screen of the device. After the patient performed maximal isometric contraction this is recorded by the device. The physiotherapist in charge will set the threshold which will be the value of the muscular contraction the patient should accomplish during his exercise, e.g. during periods of active muscular contraction. The patient should contract the muscle above the threshold which is visible on the screen. The threshold is set to 80% of the maximal isometric contraction achieved at the start of the session. Biofeedback-assisted exercise consists of isometric contractions of the m. quadriceps femoris for 15 minutes (10 seconds periods of contraction and 10 seconds periods of relaxation between contractions). Intervention will be provided once per day, face to face, by physiotherapist in a special hospital for rehabilitation. Adherence to the treatment will be monitored by physiotherapist in charge.